In the recent years, ink-jet recording systems, which enable simple formation of images at low cost, have been applied to printing fields such as photography, various types of printing, and special printing such as marking and color filters. Specifically, by employing ink-jet recording apparatuses which eject controlled minute dots of ink, ink-jet inks which have been improved in color reproduction, durability, and ejection adaptability, and specialized paper media which have been enhanced in color forming properties of colorants and surface glossiness, it has become possible to achieve image quality comparable to conventional silver halide photography. Image quality of the present ink-jet recording systems is enhanced only when an ink-jet recording apparatus, an ink-jet ink and a specialized paper medium are simultaneously improved.
However, ink-jet systems which require specialized kinds of paper result in problems such that the recording media are limited and using such recording media increases cost. Accordingly, many trials have been made in which recording, employing the ink-jet systems, is carried out on transfer media of differing specialized kinds of paper. Specific systems include a phase-changing ink-jet system employing a wax ink which is solid at room temperature, a solvent based ink-jet system employing, as a main component, rapidly drying organic solvents, and an active ray curable ink-jet system in which, after recording, active rays such as ultraviolet rays (UV) are exposed onto the deposited ink to result in cross-linking.
Of these, the UV ray curable ink-jet system results in relatively low unpleasant odor, compared to a solvent based ink-jet system, and start to gamer attention in recent years because of quick drying and being possible to print onto a recording medium exhibiting no ink absorbability. Various type of ultraviolet ray curable inks are proposed. (Please refer to, for example, Patent Documents 1 and 2.)
However, even though these ink-jet inks are employed, the dot diameter after deposition of ink droplets markedly varies, whereby it has been impossible to consistently form highly detailed images on various recording media in various working environments.
In ultraviolet ray curable inks, there is, for example, a radically polymerizable ultraviolet ray curable ink mainly containing an acrylic composition.
A radically polymerizable ultraviolet ray curable ink is, in polymerization mechanism, subjected to the oxygen inhibiting action in the environment the presence of oxygen, resulting in problems of deterioration of image quality due to reduced curability and also problems of wrinkling in the cured film or curling of a recording medium due to large curability shrinkage.
Patent Document 1: Unexamined Japanese Patent Application No. (hereinafter, referred to as JP-A) 6-200204.
Patent Document 2: Japanese Translation of PCT International Application Publication No. 2000-504778.